Foam seat element, mold for the production thereof and method to manufacture the mold

ABSTRACT

There is disclosed an improved seat element having a seating surface element that incorporates a plurality of peak portions and a plurality of valley portions. Preferably, the plurality of peak portions and the plurality of valley portions is incorporated in an outermost surface of the seating surface element. The term “outermost surface” is intended to include an area of the seating surface element for contact by and/or support of an occupant of the seat element and does not include, for example, grooves or trenches in which there is disposed a component for attachment of a trim cover. A process and a mold for production of such a seat element are also described.

FIELD OF THE INVENTION

In one of its aspects, the present invention relates to a foam seatelement, preferably a foam vehicular seat element. In another of itsaspects, the present invention relates to a process for producing a foamseat element, preferably a vehicular seat element. In yet another of itsaspects, the present invention relates to a mold for producing a moldedelement, preferably a molded foam seat element, more preferably a moldedfoam vehicular seat element. In yet another of its aspects, the presentinvention relates to a method for producing a mold.

DESCRIPTION OF THE PRIOR ART

Passenger seats in vehicles, such as automobiles, are typicallyfabricated from a foam (usually a polyurethane foam) material which ismolded into the desired shape and covered with an appropriate trimcover. The foamed material is selected to provide passenger comfort byproviding a resilient seat and the trim cover is selected to provide thedesired aesthetic properties.

In recent years, seats such as vehicular seats have been developed toconfer one or more of the following to the seat: comfort, climatecontrol, occupant detection and the like.

One area that has received particular attention is the provision of dualdensity or dual firmness seat components that are more dense or firmerin the peripheral portions of the seat thereby conferring to theoccupant a snug or “wrapped-in” feel. This is especially important inperformance vehicles which are designed such that turning at relativelyhigh speed may be accomplished. However, there is an ongoing challengeto balance support provided by the seat with comfort of the occupant.

Dual density or dual firmness seat elements are expensive to produceand, in many cases, alter the feel of the supporting surface of the seatonly in areas where it is perceived to be important to have differentfirmness properties. In other words, the conventional dual density ordual firmness seat elements use a generally coarse approach to provisionof variable density or firmness.

Further, dual (or multi) density or dual (or multi) firmness seatstypically require the use of two or more types of foam (e.g., molded,free rise, bead and the like) which are typically produced separatelyand secured together increasing the production time and costs of thefinal seat product. Alternatively, certain dual (or multi) firmnessseats are made by molding or otherwise securing an insert (e.g., wirecomponents, flexolators and the like) to a foam substrate.

Accordingly, it would be highly desirable to have the seat element thatcould be produced from a unitary foam element yet confer the benefits ofdual density or dual firmness seats.

It would be further advantageous if such an approach were capable ofbeing carried out using a much more finally tuned approach resulting ina seat element having a support surface that is designed for optimumcomfort regardless of the size of a particular occupant.

It would be particularly advantageous if such an improvement could beimplemented without the requirement for large capital expenditure.

SUMMARY OF THE INVENTION

It is an object of the present invention to obviate or mitigate at leastone of the above-mentioned disadvantages of the prior art.

Accordingly, in one of its aspects, the present invention provides aseat element comprising a foam substrate and a seating surface element,at least a portion of the seating surface element comprising a pluralityof peak portions and a plurality of valley portions.

In another of its aspects, the present invention provides mold forproduction of a seat element, the mold comprising a first mold portionand a second mold portion engageable to define a mold cavity, the firstmold portion having a seating surface molding element comprising aplurality of peak portions and a plurality of valley portions.

In yet another its aspects, the present invention provides a method formanufacturing a mold for production of a seat element, the moldcomprising a first mold portion and a second mold portion engageable todefine a mold cavity, the first mold portion having a first moldingsurface comprising a seating surface molding element, the seat surfacemolding element comprising a plurality of peak portions and a pluralityof valley portions, the method comprising the steps of:

-   -   forming an insert having a negative of the seating surface        molding element;    -   placing the insert in a first temporary mold portion such that        the combination of the insert and the first temporary mold        portion corresponds substantially to the first molding surface        of the first mold portion;    -   forming a second temporary mold portion having a negative of the        first temporary mold portion;    -   disposing a casting composition on the second temporary mold        portion;    -   forming a third temporary mold portion on an exposed portion of        the casting composition, the second temporary mold portion and        the third temporary mold portion combining to define a temporary        mold having a mold cavity occupied by the casting composition;    -   removing the casting composition from the temporary mold;    -   dispensing a mold material in the mold cavity; and    -   removing the second temporary mold portion and the third        temporary mold portion to produce the first mold portion.

Thus, the present inventors have discovered an improved seat elementhaving a seating surface element that incorporates a plurality of peakportions and a plurality of valley portions. Preferably, the pluralityof peak portions and the plurality of valley portions is incorporated inan outermost surface of the seating surface element. The term “outermostsurface” is intended to include an area of the seating surface elementfor contact by and/or support of an occupant of the seat element anddoes not include, for example, grooves or trenches in which there isdisposed a component for attachment of a trim cover.

In a more preferred embodiment, in a resting (i.e., unoccupied) state ofthe seat element, the ratio of the contact surface area (peaks only) ofthe seating surface element to the surface area of the seating surfaceelement is less than 1.

In a further preferred embodiment, the present seat element comprises amolded foam seat element, more preferably a molded foam elementcomprising a unitary foam portion. An advantage of using such a moldedfoam element in the present seat element is the presence of a skin onthe surface of the seating surface element. The presence of the skin ischaracterized by the foam having a greater density at the surface (e.g.,1 mm depth) as compared to the central or core region. Density can bedetermined using ASTM D-3574. While not wishing to be bound by anyparticular theory or mode of action, it is believed that the presence ofsuch a skin (e.g., as distinct from the case where the peaks are simplyglued to and/or the valleys are simply cut out of the seating surfaceelement) confers a desirable combination of support and comfort to anoccupant of the seat element.

The present seat element has a number of advantages, including one ormore of the following:

-   -   it is possible to achieve in a single density foam part the        “dual firmness” (or multi-firmness) that is conventionally        achieved using multiple density foam pieces in a seat        element—the terms “dual firmness” and “multi-firmness” are used        interchangeably through this specification as are the terms        “dual density” and “multi-density”;    -   it is possible to convert conventional dual firmness split        bolsters (blades and bolsters) to a dual firmness full bolster        by applying a soft touch to the inboard bolster area;    -   it is possible to use the present seat element to confer the        soft touch feel as an alternative to conventional so-called plus        padding;    -   the present seat element has improved ventilation, optionally in        combination with climate control seat technology;    -   the present seat element is expected to have improved acoustical        features;    -   the present seat element has improved comfort both in fixed and        adjustable lumbar areas;    -   the present seat element has improved comfort in thigh support        areas;    -   the present seat element can be used to improve trim cover        effects leading to improved craftsmanship;    -   the present seat element can be used to obviate or mitigate the        use of foam inserts (e.g., border wire foam inserts, felt        material and the like) conventionally used for bolster        reinforcement;    -   the present seat element can be used in so-called thin seating        applications;    -   the present seat element provides improved comfort for        non-vehicular seating applications such as marine, motorcycle        and office furniture applications;    -   biological effects such as improved blood flow, reduced muscle        fatigue, reduced shear stress and the like can accrue from use        of the present seat element; and/or    -   the present seat element can be used in energy management foam        applications by providing two distinct layers of crush/impact        zones rather than a single layer.

Of course, those of skill in the art will recognize other advantagesaccruing from the present seat element based on the presentspecification.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will be described with reference tothe accompanying drawings, wherein like reference numerals denote likeparts, and in which:

FIG. 1 illustrates a schematic top view of a vehicular seat bottom inwhich a portion of the seating surface has been pressure mapped todenote relative pressure points created by an occupant seated on thevehicular seat bottom;

FIG. 2 illustrates a schematic view of an embodiment of pressure mappinga vehicular seat unit;

FIG. 3 illustrates a first preferred embodiment of a seat element inaccordance with the present invention;

FIG. 4 illustrates a second preferred embodiment of a seat element inaccordance with the present invention;

FIGS. 5 a, 5 b and 5 c each illustrate an enlarged portion of seatelement in accordance with the present invention;

FIGS. 6 a, 6 b, 6 c and 6 d each illustrate various arrangements of thepatterns illustrated in FIGS. 5 a, 5 b and 5 c;

FIG. 7 illustrates a perspective view of a third preferred embodiment ofa seat element in accordance with the present invention;

FIG. 8 illustrates a sectional view through line A-A in FIG. 7;

FIG. 9 illustrates a sectional view through line B-B in FIG. 7;

FIG. 10 illustrates a sectional view through line C-C in FIG. 7;

FIGS. 11 a, 11 b and 11 c each illustrate a further embodiment of atextured surface repeating pattern that can be used in the present seatelement;

FIGS. 12-32 illustrate, in a step-wise manner, production of a firstmold section to be used in the present mold; and

FIG. 33 illustrates a perspective view of an embodiment of the presentmold.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Accordingly, an aspect of the present invention relates to a seatelement. Preferably, a seat element is comprised in a vehicular orpassenger seat. As used throughout this specification, the term “seat”is intended to have its conventional meaning and includes one or both ofa bottom or cushion (i.e., the portion of the seat on which the occupantsits) and a back or backrest (i.e., the portion of the seat whichsupports the back of the occupant). As is known in the automotive,airline and related industries, a “seat” includes both a cushion (orbottom) and a back (or backrest). Thus, the term “seat” includes a seatelement such as a cushion (or bottom), a back (or backrest) or a unitconstruction comprising a cushion (or bottom) and a back (or backrest).It should also be mentioned that a seat element may be considered to bea cushion (or bottom), a back (or backrest), a headrest and/or anarmrest.

While highly preferred embodiments of the present invention will beillustrated with reference to a vehicular seat element, in particular aseat cushion (or bottom), it will be appreciated that the present seatelement can be used in non-vehicular applications such as domestic andoffice furniture, stadium seating, theatre seating and the like.

With reference to FIG. 1, there is illustrated a schematic top view of avehicular seat bottom in which a portion of the seating surface has beenpressure mapped to denote relative pressure of an occupant seated on thevehicular seat bottom.

The pressure seat map illustrated in FIG. 1 can be generated in aconventional manner within the purview of a person of ordinary skill inthe art. Once generated, the pressure map is useful insofar as itillustrates areas of relative pressure on the seating surface that aregenerated when occupant sits on that surface.

Thus, in FIG. 1, there is illustrated a seat bottom 10 having a pair ofwinged portions 12 and 14, and a seating surface 16. In the exampleshown in FIG. 1, the pressure map comprises three distinct pressurezones: a low pressure zone 17, a pair of intermediate pressure zones 18and a pair of high pressure zones 19. It is to be understood that theterms “low pressure”, “intermediate pressure” and “high pressure” areused in a relative sense and that within each zone there can be somevariation in pressure. In a typical pressure map, such variation may becolour coded.

By assessing areas of pressure generated by a typical occupant in such amanner, it is possible to identify the locations on seating surface 16(and possibly on winged portions 12,14) in which it is desirable tomanage surface response to the forces generated by a seated occupant.

With reference to FIG. 2, there is illustrated a perspective view of avehicular seat 20 comprising seat bottom 10 described with reference toFIG. 1 and a seat back 11 connected thereto.

The following portions in vehicular seat 20 contain support surfaces inwhich it may be desirable to manage the response of the surface topressure from a typical occupant seated in vehicular seat 20: A, B, C, Dand E. The precise location and dimension of these portions of thesurface can be determined using pressure mapping technique describedabove with reference to FIG. 1. As stated with reference to FIG. 1, incertain cases, it may be desirable to design a managed surface responsein one or both winged portions 12 and 14 in seat bottom 10. Further, itmay be desirable to design a managed surface response in shouldersupport portions 13 and 15 in seat back 11.

With reference to FIGS. 3 and 4, there are illustrated specificembodiments of a seat bottom. In FIGS. 3 and 4, similar referencenumerals are used as in FIG. 1. In FIG. 3, the suffix “a” has been usedto denote like elements with respective FIG. 1. In FIG. 4, the suffix“b” has been used to denote like elements with respective FIG. 1.

In FIG. 3, a series of grooves 19 a is molded into seating surface 16 ato provide a managed surface response to relatively high pressureimposed on that portion of seating surface 16 a in response to anoccupant seating on seat bottom 10 a. As will be seen, this managedsurface response corresponds generally to the location of intermediatepressure zones 18 and high pressure zones 19 generated from the pressuremap shown in FIG. 1.

With reference to FIG. 4, it will be seen that seating surface 16 bincludes a plurality of recesses 19 b which are arranged to provide amanaged surface response to the portion of seating surface 16 b that isexpected to experience a relatively high force in response to anoccupant sitting on seating surface 16 b.

With reference to FIGS. 5 a, 5 b and 5 c, there are illustratedcross-sectional views of various preferred embodiments of the portion ofthe seat element surface on which it is desired to implement a managedsurface response. In other words, the remaining portion of the seatelement has not been shown for clarity.

In FIG. 5 a, there is illustrated a surface 100 a comprising a series ofpeaks 105 a and valleys 110 a. As show, each peak 105 a comprises a flatapex and each valley 110 a comprises a flat floor (or nadir portion).Peaks 105 a and valleys 110 a combine to define a series of projections115 a that are generally in the shape of a trapezoid, more particularly,a bi-laterally symmetrical trapezoid.

In FIG. 5 b, a suffix “b” has been added after each reference numeral todenote similar elements with respect to FIG. 5 a. Thus, in FIG. 5 b, itwill be seen that peaks 105 b have a round a pecks whereas valleys 110 bhave a rounded floor (or nadir portion). Further, peaks 105 b andvalleys 110 b combine to define a series of projections 115 which, incross-section, are generally bell-shaped.

In FIG. 5 c, a suffix “c” has been added after each reference numeral todenote similar elements with respect to FIG. 5 a. Thus, in FIG. 5 c, itwill be seen that peaks 105 c have a rounded apex whereas valley 110 chave a flat floor (or nadir portion). Further, it will be seen thatpeaks 105 c and valleys 110 c combine to form a series of projections115 c that, in cross-section, have a substantially parabolic shape.

As will be appreciated by those of skill in the art, the specificembodiments illustrated in FIGS. 5 a, 5 b and 5 c are exemplary innature. Those of skill in the art having in hand the presentspecification will be able to modify the specifically illustratedembodiments or design other embodiments that have peaks and valleys, andare otherwise useful in the present seat element.

With reference to FIGS. 6 a, 6 b, 6 c and 6 d, there is illustrated, inschematic form, a top view of a seat element in accordance with thepresent invention. In FIGS. 6 a, 6 b, 6 c and 6 d, a series ofprojections is shown as 115 (no suffix). Projections 115 can be of theform illustrated in FIGS. 5 a, 5 b and 5 c or in any other shapeprojection that provides a desirable managed surface response.

FIG. 6 a illustrates projections 115 in a parallel row or radiator-typearrangement. FIG. 6 b illustrates projections 115 in a diagonalarrangement. FIG. 6 c illustrates projections 115 in a checkerboard-typearrangement and FIG. 6 d illustrates projections 115 in a diamond-typepattern. Of course, those with skill in the art, having the presentspecification in hand, will be able to immediately reduce to practicemany other arrangements of projections 115 using the cross-sectionsshown in FIGS. 5 a, 5 b and/or 5 c, or other cross-sectional shapes.

With reference to FIGS. 7-10, there is illustrated a preferred seatbottom 150 having multiple sections that provide a managed surfaceresponse.

Generally, seat bottom 150 comprises a unitary foam element 152 that canbe made from polyurethane foam, polypropylene foam, polyethylene foamand the like (polyurethane foam is the most preferred foam).

Seat bottom 150 comprises a primary seating surface 154. Primary seatingsurface 154 comprises a first textured surface 160, a second texturedsurface 170 and third textured surface 180.

Seat bottom 150 further comprises a pair of winged portions 156,158.Each winged portion 156,158 comprises a fourth textured surface 190.

First textured surface 160 comprises projections similar to projections115 a in FIG. 5 a arranged in a pattern similar to the one illustratedin FIG. 6 a.

Second textured surface 170 comprises a series of projections that havea substantial rectangular shape in a pattern such as the one illustratedin FIG. 6 c.

Third textured surface 180 comprises a series of projections made up ofpeaks having a generally flat apex 181 and a series of valleys having arounded floor 182 (or nadir portion) arranged in a pattern similar tothat shown in FIG. 6 b. It will be noted that the depth of valleys 182increases from the middle of seating surface 154 to the peripherythereof.

Fourth textured surface 190 is disposed on each of winged portions156,158 and runs along the length of first textured surface 160 andsecond textured surface 170. Forth textured surface 190 comprises tworows of cup-shaped portions having a rounded valley 191 (or nadirportion). Seat bottom 150 further comprises a series of grooves 159which serves to isolate first textured surface 160, second texturedsurface 170, third textured surface 180 and fourth textured surface 190.In a preferred embodiment series of grooves 159 also serves to havedisposed therein a suitable trim cover attachment system (e.g., hog-ringwires, touch fasteners such as Velcro™-type fasteners, mechanical clipsand the like).

FIG. 11 a illustrates an enlarged perspective view of a textured surface100 d comprising a series of semi-spheroid shaped projections 115 d.Projections 115 d comprise rounded peaks 105 d and a substantiallycontinuous floor 110 d which act as a “valley”.

FIG. 11 b illustrates an enlarged perspective view of a textured surface100 e comprising a series of elongate projections 115 e. Projections 115d comprise elongate flat peaks 105 e and a substantially elongate roundfloor 110 e.

FIG. 11 c illustrates an enlarged perspective view of a textured surface100 f comprising a series of projections 115 f. Projections 115 fcomprise flat peaks 105 e and a substantially ogival or rounded valley(or nadir portion) 110 e.

With reference to FIGS. 12-32, there is illustrated a stepwise processto producing mold capable of forming a seat element having a texturessurface such as shown in FIG. 3 described above.

With reference to FIG. 12, a machined master form 200 is produced in aconventional manner (typically from aluminum, wood or any othersufficiently durable material). Machined master form 200 has a negativeof the desired texture surface to be conveyed to the seat element.

With reference to FIG. 13, machined master form 200 is disposed in acontainer 205 comprising a base 210 and a pair of side walls 215. Aresin (e.g., urethane, silicone and the like) composition 220 isdispensed atop machined master form 200 in a conventional manner.

After epoxy resin 220 has cured, it is removed from machined master form200 to yield a cast resin form 225 having the textured surface to beconveyed to the product eventually to be molded—see FIG. 14.

Cast resin form 225 is placed in container 225 (or another container). Aurethane-forming mixture 230 is dispensed atop as resin form 225 in aconventional manner. Urethane forming mixture 230 is allowed to cure andis thereafter removed from container 200 to yield urethane mat 235 whichhas the same textured surface as machined master form 200—see FIG. 16.

With reference to FIG. 17, a model 240 of the finished seat element isconstructed without the textured surface. Model 240 may be constructedfrom wood or any other material that is sufficiently durable towithstand the mold manufacturing process.

With reference to FIG. 18, model 240 is mounted on a follow board 245having a seal block area 250.

With reference to FIG. 19, model 240 mounted on follow board 245 is thanplaced in a containment box 255.

Next, with reference to FIG. 20, the exposed surfaces of model 240,follow board 245, seal block 250 and a portion of containment box 255are covered with a layer of plaster (or other curable) material 260.Once plaster material 260 has cured (or otherwise requires sufficientintegrity to be handled), follow board 245, seal block 250 andcontainment box 255 are removed while leaving model 240 with plastercomposition 260—see FIG. 21.

With reference to FIG. 22, a lid containment box 265 is placed aroundthe marginal edges of plaster composition 260.

Next, plaster (or other curable) composition 270 is dispensed on exposedportions of model 240, plaster composition 260 and a portion of lidcontainment box 265—see FIG. 23. Once plaster composition 270 has beencured (or otherwise acquires sufficient integrity), the bowl patternformed by plaster composition 260 is separated from the lid pattern formby plaster composition 270 and model 240 is removed.

With reference to FIG. 24, mat 235 (FIG. 16) is disposed as illustratedin the bowl pattern formed by plaster composition 260.

Thereafter, a foundry containment box 275 is disposed around themarginal edges of the bowl formed by plaster composition 260—see FIG.25.

Next, a sand-based (or plaster-based) foundry composition 280 isdispensed in the bowl formed by plaster composition 260 and is containedwithin foundry containment box 275.

With reference to FIG. 26, once the sand-based foundry composition hascured, it is separated from the bowl formed by plaster composition 260and foundry containment box 275, and mat 235 is removed therefrom.

With reference to FIG. 27, a clay (or other malleable) composition 285is applied over the surface of sand-based foundry composition 280 at athickness equivalent to the desired thickness of the mold to bemanufactured.

Next, a foundry containment box 290 is placed around sand-based foundrycomposition 280 and further sand-based foundry composition 295 is placedatop the exposed portions of clay composition 285, sand-based foundrycomposition 280 and exposed portions of foundry composition 290—see FIG.28. With reference to FIG. 29, once sand-based foundry composition 295has cured, it is separated from foundry containment box 290, claycomposition 285 and sand-based foundry composition 280.

Next, the forms defined by sand-based foundry compositions 280 and 295are recombined to define a mold cavity 297—see FIG. 30.

An aperture 293 or other port is drilled or otherwise created in theform produced by sand-based foundry composition 295 and molten aluminum299 is dispensed therethrough using a conventional gating system to fillmold cavity 297. Molten aluminum 299 is allowed to cool after whichsand-based foundry compositions 280 and 295 are broken away therebyyielding lower mold section 300—see FIGS. 31 and 32.

Various of the steps shown above with reference to FIGS. 17-30 may berepeated to produce a lid portion 305 of the mold shown in FIG. 33. Forexample, with reference to FIG. 23, the form produced by plastercomposition 270 may be used in steps such as those appearing in FIGS. 25(excluding insert 235) and 27-30. If it is not desired to have atextured surface produced by lid portion 305 of the mold shown in FIG.33, the use of mat 235 is not necessary in the production of lid portion305.

While this invention has been described with reference to illustrativeembodiments and examples, the description is not intended to beconstrued in a limiting sense. Thus, various modifications of theillustrative embodiments, as well as other embodiments of the invention,will be apparent to persons skilled in the art upon reference to thisdescription. For example, in the process to produce the present mold, ifthe design of the seating surface element incorporating the plurality ofpeaks and the plurality of valleys is not highly contoured, it ispossible produce a machined master form as shown in FIG. 14 without theneed to carry out the steps shown in FIGS. 12 and 13. Further, itspossible to use materials other than the plaster compositions andsand-based foundry composition specifically referred to with referenceto FIGS. 17-30. Still further, it is possible to adopt patterns otherthan those shown in FIGS. 6 a, 6 b, 6 c and 6 d—e.g., a herringbonepattern, a triangular pattern, a polygonal pattern containing more thanfour sides and the like. It is therefore contemplated that the appendedclaims will cover any such modifications or embodiments. Further, all ofthe claims are hereby incorporated by reference into the description ofthe preferred embodiments.

All publications, patents and patent applications referred to herein areincorporated by reference in their entirety to the same extent as ifeach individual publication, patent or patent application wasspecifically and individually indicated to be incorporated by referencein its entirety.

1. A seat element comprising a foam substrate and a seating surfaceelement, at least a portion of the seating surface element comprising aplurality of peak portions and a plurality of valley portions. 2-156.(canceled)